﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace QFrameworkOne.Module {
    /// <summary>
    /// Base64加密解密模块
    /// </summary>
    public class QBase64 : IQMoudule {
        string IQMoudule.Module_Name => "Base64加密解密模块";

        string IQMoudule.Module_Author => "DA";

        string IQMoudule.Module_Mail => "admin@deali.cn";

        string IQMoudule.Module_Website => "http://deali.cn";

        string IQMoudule.Module_Description => "多种方法实现Base64加密解密";

        QComponentVersion IQMoudule.Module_Version => new QComponentVersion() {
            Major = 1,
            Minor = 0,
            Update = 1,
            Label = QComponentVersionLabel.Alpha
        };

        /// <summary>
        /// Base64加密
        /// </summary>
        /// <param name="encode">加密采用的编码方式</param>
        /// <param name="source">待加密的明文</param>
        /// <returns></returns>
        public string SysEncodeBase64(Encoding encode, string source) {
            byte[] bytes = encode.GetBytes(source);
            string base64Str = null;
            try {
                base64Str = Convert.ToBase64String(bytes);
            }
            catch {
                base64Str = source;
            }

            return base64Str;
        }

        /// <summary>
        /// Base64加密，采用utf8编码方式加密
        /// </summary>
        /// <param name="source">待加密的明文</param>
        /// <returns>加密后的字符串</returns>
        public string SysEncodeBase64(string source) {
            return SysEncodeBase64(Encoding.UTF8, source);
        }

        /// <summary>
        /// Base64解密
        /// </summary>
        /// <param name="encode">解密采用的编码方式，注意和加密时采用的方式一致</param>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public string SysDecodeBase64(Encoding encode, string result) {
            string decode = "";
            byte[] bytes = Convert.FromBase64String(result);
            try {
                decode = encode.GetString(bytes);
            }
            catch {
                decode = result;
            }

            return decode;
        }

        /// <summary>
        /// Base64解密，采用utf8编码方式解密
        /// </summary>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public string SysDecodeBase64(string result) {
            return SysDecodeBase64(Encoding.UTF8, result);
        }


        /// <summary>
        /// Base64编码
        /// </summary>
        /// <param name="Message"></param>
        /// <returns></returns>
        public string EncodeBase64(string Message) {
            char[] Base64Code = new char[] {
                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',

                'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',

                'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',

                '8', '9', '+', '/', '='
            };

            byte empty = (byte) 0;

            System.Collections.ArrayList byteMessage =
                new System.Collections.ArrayList(System.Text.Encoding.Default.GetBytes(Message));

            System.Text.StringBuilder outmessage;

            int messageLen = byteMessage.Count;

            int page = messageLen / 3;

            int use = 0;

            if ((use = messageLen % 3) > 0) {
                for (int i = 0; i < 3 - use; i++)

                    byteMessage.Add(empty);

                page++;
            }

            outmessage = new System.Text.StringBuilder(page * 4);

            for (int i = 0; i < page; i++) {
                byte[] instr = new byte[3];

                instr[0] = (byte) byteMessage[i * 3];

                instr[1] = (byte) byteMessage[i * 3 + 1];

                instr[2] = (byte) byteMessage[i * 3 + 2];

                int[] outstr = new int[4];

                outstr[0] = instr[0] >> 2;

                outstr[1] = ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);

                if (!instr[1].Equals(empty))

                    outstr[2] = ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);

                else

                    outstr[2] = 64;

                if (!instr[2].Equals(empty))

                    outstr[3] = (instr[2] & 0x3f);

                else

                    outstr[3] = 64;

                outmessage.Append(Base64Code[outstr[0]]);

                outmessage.Append(Base64Code[outstr[1]]);

                outmessage.Append(Base64Code[outstr[2]]);

                outmessage.Append(Base64Code[outstr[3]]);
            }

            return outmessage.ToString();
        }

        /// <summary>
        /// Base64解码
        /// </summary>
        /// <param name="Message"></param>
        /// <returns></returns>
        public string DecodeBase64(string Message) {
            if ((Message.Length % 4) != 0) {
                throw new ArgumentException("不是正确的BASE64编码，请检查。", "Message");
            }

            if (!System.Text.RegularExpressions.Regex.IsMatch(Message, "^[A-Z0-9/+=]*$",
                System.Text.RegularExpressions.RegexOptions.IgnoreCase)) {
                throw new ArgumentException("包含不正确的BASE64编码，请检查。", "Message");
            }

            string Base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

            int page = Message.Length / 4;

            System.Collections.ArrayList outMessage = new System.Collections.ArrayList(page * 3);

            char[] message = Message.ToCharArray();

            for (int i = 0; i < page; i++) {
                byte[] instr = new byte[4];

                instr[0] = (byte) Base64Code.IndexOf(message[i * 4]);

                instr[1] = (byte) Base64Code.IndexOf(message[i * 4 + 1]);

                instr[2] = (byte) Base64Code.IndexOf(message[i * 4 + 2]);

                instr[3] = (byte) Base64Code.IndexOf(message[i * 4 + 3]);

                byte[] outstr = new byte[3];

                outstr[0] = (byte) ((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));

                if (instr[2] != 64) {
                    outstr[1] = (byte) ((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));
                }

                else {
                    outstr[2] = 0;
                }

                if (instr[3] != 64) {
                    outstr[2] = (byte) ((instr[2] << 6) ^ instr[3]);
                }

                else {
                    outstr[2] = 0;
                }

                outMessage.Add(outstr[0]);

                if (outstr[1] != 0)

                    outMessage.Add(outstr[1]);

                if (outstr[2] != 0)

                    outMessage.Add(outstr[2]);
            }

            byte[] outbyte = (byte[]) outMessage.ToArray(Type.GetType("System.Byte"));

            return System.Text.Encoding.Default.GetString(outbyte);
        }
    }
}